Disorders in the stumps of amputee patients: MR imaging.
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Biomedical subjects
Publications and source records attributed to R D Boutin.
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Cartilage injury resulting in osteoarthritis is a frequent cause of disability in young people. Osteoarthritis, based on either cartilage injury or degeneration, is a leading cause of disability in the United States. Over the last several decades, much progress has been made in understanding cartilage injury and repair. Magnetic resonance (MR) imaging, with its unique ability to noninvasively image and characterize soft tissue, has shown promise in assessment of cartilage integrity. In addition to standard MR imaging methods, MR imaging contrast mechanisms under development may reveal detailed information regarding the physiology and morphology of cartilage. MR imaging will play a crucial role in assessing the success or failure of therapies for cartilage injury and degeneration.
PURPOSE: To determine a set of distinctive imaging findings seen in symptomatic patients with pretibial varices. MATERIALS AND METHODS: Medical records and imaging studies of patients who presented with pretibial varices over an 8-year period were collected from four institutions. Findings in six symptomatic patients with pretibial varices were retrospectively reviewed. Radiographic and magnetic resonance (MR) imaging findings were available from all six patients; findings from several other modalities were also available in some patients. RESULTS: Conventional radiographs showed a small osteolytic defect in the anterior cortex of the midtibia and a prominent, longitudinally oriented, radiolucent groove in the proximal half of the tibial diaphysis. MR images showed pretibial varices connected to an enlarged vessel in the tibia that eventually exited through the nutrient foramen. Computed tomographic (three patients), sonographic (four patients), venographic (four patients), arteriographic (two patients), and surgical (three patients) findings demonstrated that these patients had an unusual intraosseous varix that traversed the anterior cortex, medullary cavity, and posterior cortex of the tibia. CONCLUSION: Recognition of these findings can prevent misdiagnosis and may prove helpful in the planning of appropriate treatment.
PURPOSE: To evaluate short echo time (TE) projection reconstruction magnetic resonance (MR) imaging in the detection of cartilage lesions. MATERIALS AND METHODS: Twenty-seven cartilage regions of 10 human patellar specimens were examined with the following MR sequences: short TE projection reconstruction (repetition time msec/TE msec, 400/0.15), fat-suppressed three-dimensional spoiled gradient-recalled acquisition in the steady state (Spoiled GRASS) (50/10, 60 degrees flip angle), and magnetization transfer contrast (MTC) subtraction (400/6). MR findings were correlated with histopathologic grading of the cartilage. RESULTS: For detection of cartilage lesions, sensitivity of projection reconstruction imaging (100%) was significantly greater (P = .03) than that of MTC (62%) but not significantly greater (P > .05) than that of Spoiled GRASS (81%) imaging. Accuracy of projection reconstruction was significantly greater than that of MTC (P = .004) and Spoiled GRASS (P = .03) imaging. Unmasking of collagen fibers was most predictive of abnormal signal intensity of the cartilage with all sequences. CONCLUSION: In vitro, short TE projection reconstruction MR imaging provides superior delineation of cartilage lesions when compared with two other sequences. On Spoiled GRASS and MTC images, signal intensity of the superficial layer of cartilage is not a reliable sign for surface integrity.
PURPOSE: To investigate the feasibility of applying magnetic resonance (MR) imaging with use of an anionic compound, Gd(DTPA)2- (gadolinium diethylenetriamine-pentaacetic acid), for measuring glycosaminoglycan concentration in human cartilage in clinical studies. MATERIALS AND METHODS: Penetration of Gd(DTPA)2- into cartilage was monitored through sequential T1-calculated images obtained after intraarticular (n = 2) or intravenous (n = 2) injection. T1-weighted and T1-calculated image series were then obtained in seven volunteers (nine knees) after penetration of Gd-(DTPA)2- into cartilage. If T1 was heterogeneous on Gd(DTPA)(2-)-enhanced images, images were also obtained after penetration of the cartilage with the nonionic contrast agent, gadoteridol. RESULTS: Gd(DTPA)2- penetrated cartilage from the articular surface after intraarticular injection and from both the articular surface and the subchondral bone after intravenous injection. The latter resulted in shorter overall penetration time. T1 values on Gd(DTPA)(2-)-enhanced images were homogeneous in four knees, but in five knees T1 differences of up to 30% were observed. These T1 differences were not seen in the presence of gadoteridol. These variations in T1 reflected about 50% variations in glycosaminoglycan. CONCLUSION: The data suggest that Gd(DTPA)(2-)-enhanced MR imaging has potential for monitoring glycosaminoglycan content of cartilage in vivo.
MR imaging has had a limited role in the evaluation of arthritis involving the shoulder, despite studies that have shown this technique to be more sensitive than radiography in the evaluation of osseous erosions and cartilage loss. Factors responsible for limiting the use of MR imaging are its relatively high cost, as well as its insensitivity to diminished osseous mineralization and subtle areas of calcification or hyperostosis. MR imaging findings of some arthropathies, however--such as synovial osteochondromatosis, PVNS, and amyloid arthropath--are highly characteristic, and help in determining both diagnosis and treatment. Physicians also should be aware that MR imaging is highly effective at diagnosing numerous "secondary" conditions common in patients with shoulder arthropathies, including rotator cuff rupture, synovial cyst formation, and osteonecrosis.
Neoplasms of bone can arise from any of the cellular elements that constitute osseous tissues. Although tumors of vascular origin are not uncommon, the vast majority are benign. A rare malignant vascular tumor--epithelioid hemangioendothelioma of bone--classifically affects young males and produces osteolytic lesions involving the cortex and cancellous bone of the lower extremities. We present a case with these findings, as well as such unusual findings as cervical spine instability and lesions affecting no fewer than 45 different bones. We conclude that epithelioid hemangioendothelioma should be investigated by skeletal survey because (1) osteolytic lesions involving more that 50% of the cortex present a serious risk for pathologic fracture and (2) the natural history of multicentric epithelioid hemangioendothelioma is more indolent than its solitary counterparts.
In the inevitable cost-benefit analysis to come, the appropriate role of MR arthrography will rightly be challenged. As arthroscopic and MR imaging techniques become even more widespread and refined, a well-defined niche for MR arthrography will eventually emerge.
OBJECTIVE: The purpose of this study was to survey the methods used by academic institutions for identifying patients who might have metallic foreign bodies or other contraindications to MR imaging. We also sought to determine the types of MR-related injuries and any subsequent legal action that might have occurred at these institutions. MATERIALS AND METHODS: A survey on these issues was mailed to 207 academic institutions listed in the American Medical Association's Directory of Graduate Medical Education Programs. Institutions that did not respond by mail were contacted by phone. The survey requested information on the use of questionnaires, plain radiography, CT, and metal detectors for screening potential MR imaging subjects, as well as on any MR-related injuries and subsequent legal action. Responses were entered into a data base and response percentages were calculated for each question. RESULTS: The overall response rate for the survey was 99% (206/207). These 206 institutions have a total of 368 MR imaging units, with a mean number of 1.8 MR units per department (range, none to nine). Data from a total of 205 different sites revealed that all patients are screened before MR imaging with a written questionnaire at 93% of all institutions (190/205). For selected indications, 85% of departments (174/205) screen with plain film radiography of the orbits. For selected indications, 41% of facilities (83/205) screen with CT of the orbits. Patients are sometimes screened with a metal detector or magnetometer in 12% of the departments (24/205). Ten departments reported serious injuries relating to MR imaging. The most serious injury occurred when an oxygen tank near the magnet became a missile and struck a patient's face. Most injuries (nine of 14) were burns. Two institutions also reported adverse reactions to gadopentetate dimeglumine. Injuries prompted legal action against four of the 10 institutions. No injuries were related to intraorbital foreign bodies, vascular clips, or pacemakers in patients. CONCLUSION: These data demonstrate the lack of consensus on screening protocols before MR imaging. Accidents are uncommon, but most accidents that do occur are potentially severe and easily preventable. We recommend that all patients be screened by a written questionnaire followed by oral questioning before imaging to determine those who are at risk. Specific questions should investigate the possibility that patients have ferromagnetic foreign bodies or implants anywhere in the body that are electrically, magnetically, or mechanically activated. All facilities must maintain a high state of vigilance in an effort to prevent iatrogenic burns and injuries from ferromagnetic missiles.
OBJECTIVE: The purpose of this study was to measure the prevalence of metallic foreign bodies in the orbits of 15,024 patients who were scheduled for MR imaging during a 4-year period and to determine if screening by plain radiography, CT, or both before MR imaging is efficacious. MATERIALS AND METHODS: Records of 15,024 patients scheduled for MR imaging were reviewed. A total of 1593 patients who had identified themselves as being at risk for an intraorbital metallic foreign body had undergone plain radiography or CT of the orbits. Plain radiographs and/or CT scans of patients reported as having orbital metal were reviewed to confirm the presence of a metallic foreign body and to identify its location. RESULTS: Metallic foreign bodies were discovered in 40 patients. Six of these patients had impaired vision in the involved eye. Ten patients had a metallic foreign body in or near the orbit but well away from the globe and were thought to be at low risk for movement of the foreign body as a result of MR imaging. The other 24 patients had metallic foreign bodies adjacent to or within the globe and were thought to be at risk for movement of the metallic foreign body as a result of MR imaging. CONCLUSION: The prevalence of intraorbital metallic foreign bodies in our study population was low (0.27%). Even in those patients identified as being at risk, the prevalence was only 2.5%. Based on the number of MR examinations performed annually in the United States and on data indicating that no radiographic screening is performed at 5% of institutions, we extrapolate that more than 2400 patients with intraorbital metallic foreign bodies have undergone MR imaging since 1986 without report of injury. These data allow us to infer that the risk of eye damage for patients who have intraorbital metal is low and that radiographic screening before MR imaging is not needed as often as it is done.
The Scientific Board of the California Medical Association presents the following inventory of items of progress in radiology. Each item, in the judgment of a panel of knowledgeable physicians, has recently become reasonably firmly established, both as to scientific fact and important clinical significance. The items are presented in simple epitome, and an authoritative reference, both to the item itself and to the subject as a whole, is generally given for those who may be unfamiliar with a particular item. The purpose is to assist busy practitioners, students, researchers, or scholars to stay abreast of these items of progress in radiology that have recently achieved a substantial degree of authoritative acceptance. Whether in their own field of special interest or another. The items of progress listed below were selected by the Advisory Panel to the Section on Radiology of the California Medical Association, and the summaries were prepared under its direction.
Adrenal cysts are uncommon lesions with only approximately 300 having been reported to date. Histologically, they are heterogeneous in nature with angiomatous endothelial cysts being quite rare. The computed tomography of a woman with a very large cyst of this variety displayed thin walls with a few septations and foci of soft tissue within. The possibility of a large cystic mass originating from the adrenal gland must be considered in the diagnosis when a large abdominal mass is encountered.